El Nino is building, beginning a havoc-wreaking weather pattern that brings floods to the deserts of southern California and droughts to the Pacific Northwest.

“The Boy,” named for its appearance around Christmas, is a periodic warming of the South Pacific that occurs every two to eight years and turns the weather patterns in North America topsy-turvy for about five months before subsiding.

For Colorado, the effects of El Nino are varied, said National Weather Service senior forecaster Chad Gimmestad. With the dropping of the jet stream, the southern part of the state generally sees more snowfall, making it a good year to plan a ski trip to Purgatory or Wolf Creek. Wyoming, on the other hand, is typically dry and warm in El Nino years.

Predicting what’s going to happen in north central Colorado during an El Nino year can be difficult, Gimmestad said. Grand and Summit counties are “right in the middle there,” between the moist, cool air in the south and the dry, warm air to the north.

“A lot of El Nino winters come out OK for central Colorado,” Gimmestad said. “Snowfall is in the realm of normalcy.”

But, Bob Henson of the National Center for Atmospheric Research wrote in UCAR Magazine on Oct. 28 that new research shows northeastern Colorado’s biggest dumps arriving during El Nino years, typically on the early and late ends of the winter season.

“A storm dropping at least 20 inches is roughly seven times more likely during El Nino,” he wrote. “Most of these monster storms occur in the fall and spring, when there’s more moisture present than in midwinter.”

November, December and January tend to be warmer and drier in this part of the state during El Nino years, the research shows.

Henson goes on to state that NOAA’s data showing “typical” snowfall in northeastern Colorado during El Nino years averages out the big dumps across the entire winter, “obscuring the impact of one big storm.”

If predictions are right, big powder skiers can look toward February and March for their best days this year.